The present inventors have already proposed a method for processing glyceride fats and oils wherein glyceride fats and oils are subjected to an ester interchange reaction in a recycle system (Japanese Patent Kokai No. 56-163196 and U.S. Pat.No. 4,420,560). This method is suitable for the production of a hard butter and, in this method, a mixture (a) of a glyceride fat or oil to be processed (b) and a fatty acid ester or fatty acid (c) is subjected to a selective ester interchange reaction, and a fatty acid ester or fatty acid (d) and a desired processed glyceride (e) present in the reaction mixture (f) are separated therefrom followed by preparing the hard butter from the glyceride (e). This method is characterized by recycling the material (d) as a part of the mixture (a). The material (d) includes an unreacted fatty acid ester or fatty acid (c), if any, and that formed by the ester interchange reaction.
However, in the above method, when a fatty acid, especially a saturated fatty acid, is used as the material (c), there is a restriction that it is necessary to use a solvent in the ester interchange reaction. In addition, there is a problem that non-selective ester interchange (isomerization) takes place during distillation for separating the materials (d) from (e) in the reaction mixture (f), which impairs the advantage brought by the selective ester interchange.
In the case that a monohydric alcohol fatty acid ester is used as the material (c) in the above method and a fatty acid ester as the material (d) is recycled repeatedly, isomerization still takes place during the distillation step for separating the material (d) from the material (e), which results in a slight deterioration of a product. Further, when the fatty acid ester (d) is recycled repeatedly, there are problems that crystals may be separated out in the mixture (a), resulting in clogging when an immobilized enzyme is used, and reactivity is lowered.
Therefore, a solution to these problems has been requested.